The imperial pint (≈ 568 ml) is used in the United Kingdom and Ireland and to a limited extent in Commonwealth nations. In the United States, two pints are used: a liquid pint (≈ 473 ml) and a less-common dry pint (≈ 551 ml). Each of these pints is one-eighth of its respective gallon but the gallons differ and the imperial pint is about 20% larger than the US liquid pint. This difference dates back to 1824, when the British Weights and Measures Act standardised various liquid measures throughout the British Empire, while the United States continued to use the earlier English measures. The imperial pint consists of 20 imperial fluid ounces and the US liquid pint is 16 US fluid ounces, making the imperial fluid ounce about 4% smaller than the US fluid ounce.

All of the other former British colonies such as Canada, Australia, South Africa and New Zealand converted to the metric system in the 1960s and 1970s, so while the term "pint" may still be in common use in these countries, it may no longer refer to the British imperial pint once used throughout the British Empire. In the United Kingdom, the imperial pint is still the primary unit for draught beer and cider, as it is for milk sold in returnable bottles. In the UK, legislation mandates that draught beer and cider may be sold by the imperial pint in perpetuity, and in public houses can only be sold in a third of a pint, two-thirds of a pint or multiples of half a pint, which must be served in stamped measured glasses or from government-stamped meters.[1]

Since the vast majority of countries in the world no longer use American or British imperial units, and most are non-English speaking, a "pint of beer" served in a tavern outside the United Kingdom and the United States may be measured by other standards. In Commonwealth countries it may be a British Imperial pint of 568 ml, in countries serving large numbers of American tourists it might be a US liquid pint of 473 ml, in many metric counties it is a half-litrebeer stein of 500 ml, or in some places it is another measure reflecting national and local laws and customs.[2]

Historically, units called a pint (or the equivalent in the local language) were used across much of Europe, with values varying between countries from less than half a litre to over one litre. Within continental Europe, the pint was replaced with the metric system during the 19th century, The term is still in limited use in parts of France, and in Quebec - where "une pinte" means an imperial quart, which is 2 pints, around one litre, whereas a pint is "une chopine" - and Central Europe, notably some areas of Germany[3] and Switzerland, colloquially used for roughly half a litre.

The French word pinte is etymologically related, but historically described a larger unit. The Royal pint (pinte du roi) was 48 French cubic inches (952.1 mL).[9] but regional pints varied in size depending on locality and on commodity (usually wine or olive oil) varying from 0.95 L to over 2 L.[9] Thus, in French Canada, une pinte refers, by federal law, to the imperial quart whereas the imperial pint is called une chopine.[10]

In Canada, if you speak English and order "a pint of beer", servers are legally required to serve you 568 ml of beer,[11] but if you speak French and order a "une pinte de bière", they are legally required to serve you 1136 ml, or twice as much. This is an example of a false cognate because the historic French pinte was about twice as large as the historic Imperial pint, and the unit still persists in Quebec. If you want a pint of beer in Quebec, order "une chopine de bière".[12]

In Flanders, the word pintje, meaning 'little pint', refers only to a 250 mL glass of lager. Some West- and East-Flemish dialects use it as a word for beaker. The equivalent word in German, Pintchen, refers to a glass of a third of a litre in Cologne and the Rhineland.

One US fluid pint of water weighs about a pound (16 ounces), resulting in the popular saying, "The pint's a pound, the world around."[citation needed] However, a US pint of water weighs 1.04375 pounds and the statement does not hold the world around because the imperial (UK) pint, which was also the standard measure in Australia, India, Malaya, New Zealand, South Africa etc., weighs 1.25 pounds. A different saying for the imperial pint is "A pint of pure water weighs a pound and a quarter."

The pint is traditionally one-eighth of a gallon. In the Latin of the apothecaries' system, octarius (plural octarii; symbol O) reflected the "eighth" concept in its octa- syllable. Because of the variety of definitions of a gallon, there have been equally many versions of the pint.

America adopted the British wine gallon, defined in 1707 as 231 cubic inches exactly (3 × 7 × 11 in) as its basic liquid measure, from which the US wet pint is derived; and the British corn gallon (1⁄8 of a standard "Winchester" bushel of corn, or 268.8 cubic inches) as its dry measure, from which the US dry pint is derived.

In 1824 the British parliament replaced all the various gallons with a new imperial gallon based on ten pounds of distilled water at 62 °F (16.667 °C) (277.42 cubic inches), from which the current UK pint is derived.

The various Canadian provinces continued to use the Queen Anne Winchester wine gallon as a basis for their pint until 1873, well after Britain adopted the imperial system in 1824. This made the Canadian pint compatible with the American pint, but after 1824 it was incompatible with the British pint. The traditional French "pinte" used in Lower Canada (Quebec) was twice the size of the traditional English "pint" used in Upper Canada (Ontario), about 1 litre versus 0.5 litres. After four of the British provinces united in Canadian Confederation in 1867, Canada legally adopted the British imperial system of measure in 1873, making Canadian liquid units incompatible with American ones from that year forward.[13] In 1873, the French Canadian "pinte" was defined as being one imperial quart or two imperial pints, while the imperial pint was legally called a "chopine" in French Canada. Canadian imperial units of liquid measure remain incompatible with American traditional units to this day, and although the Canadian pint, quart, and gallon are still legal units of measure in Canada, they are still 20% larger than the American ones.

In the British and Irish metrication processes, the pint was replaced by metric units as the legally defined primary unit of measure for trading by volume or capacity, except for the sale of draught beer and cider, and milk in returnable containers.[14] The pint can still be used in those countries as a supplementary unit in all circumstances. Local legislation in the UK mandates the use of the pint as a measure for draught beer and cider (in pubs for instance).[15][16] For milk, if returnable containers are used, the pint can still be the principal unit used, otherwise metric units (usually the non-SI litre) must be used. There is no requirement for the litre quantity to be round numbers: thus the quantity of milk sold in a non-returnable container may be 1 pint, but will have "568 ml 1 pint", or just "568 ml" on the label. Many recipes published in the UK and Ireland still give ingredient quantities in imperial, where the pint is often used as a unit for larger liquid quantities.[citation needed] The Guild of Food Writers recommends that new recipes be published in metric units.[17]

In Australia and New Zealand, a subtle change was made to 1 pint milk bottles during the conversion from imperial to metric in the 1970s. The height and diameter of the milk bottle remained unchanged, so that existing equipment for handling and storing the bottles was unaffected, but the shape was adjusted to increase the capacity from 568 ml to 600 ml – a conveniently rounded metric measure. Such milk bottles are no longer officially referred to as pints. However the "pint glass" in pubs in Australia remains closer to the standard imperial pint, at 570 ml. It holds about 500 ml of beer and about 70 ml of froth, except in South Australia where a pint is served in a 425 ml glass and a 570 ml glass is called an "imperial pint". In New Zealand, there is no longer any legal requirement for beer to be served in standard measures: in pubs, the largest size of glass, which is referred to as a pint, varies, but usually contains 425 ml.[18]

In Canada, the "pint of beer" served in pubs and bars has long been considered a colloquial term for "a large glass of beer". Legally speaking, after 1873 it was defined as one British imperial pint of 20 imperial ounces. On the other hand, the United States continued to use a smaller 16 ounce pint, while in French Canada after 1873 a "pinte de bière" was defined as a much larger 40 ounce quart of beer, so confusion arose to which was being used. Prior to 1961, bottled beer in Canada was served in two sizes, colloquially known as "quarts" and "pints." They were 22 and 12 imperial ounces (625 and 341 ml), respectively, which were much smaller than the British units. Some provinces banned the sale of beer in the larger bottle. For example, in Ontario in the 1950s only the smaller size could be sold, but in Quebec both sizes were about equally common. The numerous incompatibilities between traditional Canadian, British, French, and American unit systems was one of the driving forces behind metrication in Canada.

Draft beer in Canada, when advertised as a "pint", is legally required to be 568 ml (20 fluid ounces).[19] With the allowed margin of error of 0.5 fluid ounces, a "pint" which is less than 554 ml of beer is an offence, though - to the detriment of consumers - this regulation is often violated and rarely enforced.[20]

After metrication in Canada, companies sold milk and other liquids in metric units so conversion issues could no longer arise. Legally speaking, although some British imperial units are still legally usable in Canada, as a result of Canada's colonial history, the "pint" served in drinking establishments in Canada should be the larger 20 ounce British imperial pint, rather than the smaller 16 ounce American traditional pint. Under the Canada Weights and Measures Act, if asked for a "pint of beer", businesses should serve customers 0.568 litres of beer with an accuracy of 0.5%, and if asked for a "pinte de bière" they should serve them 1.136 litres.[21] To avoid legal issues, many drinking establishments are moving away from using the term "pint" and are selling "glasses" or "sleeves" of beer, neither of which have a legal definition.[22]

A 375 ml bottle of liquor in the US and the Canadian maritime provinces is sometimes referred to as a "pint" and a 200 ml bottle is called a "half-pint", harking back to the days when liquor came in US pints, fifths, quarts, and half-gallons.[23] Liquor in the US has been sold in metric-sized bottles since 1980 although beer is still sold in US traditional units.[24]

In France, a standard 250 ml measure of beer is known as un demi ("a half"), originally meaning a half pint.